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The photochemical fluorination of cyanogen chloride
INOI~G.
NUCL
CHEM
LETTEK~
Vol. ~,~ p~.
THE PHOTOCHEMICAL
46e~-475, 1972,
FLUORINATION
Pergamon
Press,
OF CYANOGEN
Printed
in
Great
13ritair~.
CHLORIDE
E. V. Oexler and E. H. Staricco Departamento Universidad
de Fisicoquimica, Nacional
Facultad
de Cordoba,
de Ciencias
Cordoba
Quimicas
(32), Argentina
(Received 12 danua~ i ~ 2 )
Some attention has been devoted to the fluorination gen chloride
(1-5).
W h e n silver difluoride was used as a fluorin-
ating agent at room temperature yield.
However,
at 100°C
found N2, CF3CI , CF4, products were temperatures N-F bonds
(I), CF3NNCF 3 was produced
(2), besides
CF2C12,
in high
this compound were also
CFCI 3 and CF3NNCF2CI.
A variety of
obtained when. other fluorides were employed at higher (3,4), but in none of these cases were compounds with
isolated.
At 94°C
F 2 among many compounds were
of cyano-
(5), in the reaction between CICN and
a small quantity of CF2CINF 2 and CF3NFCI
obtained. We wish to report that in an attempt
the mechanism
of the fluorination
was undertaken.
to have an insight into
of CICN a study of this system
It was found that no thermal reaction occurs
between CICN and F 2 up to 45°C,
but when the gaseous mixture was
o
irradiated with light of 3660 A, a reaction takes place, CF2CI 2 and N 2 being the major products.
469
CF3CI ,
470
PHOTOCHEMICAL FLUORINATION
Vol. 8, No. 5
Experimental CICN was prepared according to Klemenc to trap distilled at low temperature.
(6), and then trap
F 2 (Air Products) was
twice distilled between liquid oxygen and liquid nitrogen temperatures and stored in a trap cooled with liquid nitrogen. Nitrogen
(99,9%) and Argon
(99,9%) were used without further
purification. The reactor was a quartz cylinder I0 cm long;
it was con-
nected to a quartz spiral manometer used as the reference instrument of a mercury manometer. needle
Aluminum valves with nickel
stems and Teflon gaskets were employed.
The source of
light was a HBO 500 0sram lamp and by means of quartz lens, o
diaphragms and Schott filters a parallel beam of 3360 A was obtained.
The intensity of incident light, measured with a Kipp
compensated thermopile and a Microva Galvanometer,
was 4,54.1015
quantum minute-lcc -I Procedure:
Most of the experiments were carried out to only
few percent conversion.
After the period of illumination the
gaseous mixture was expanded into a trap containing mercury.
A
U-trap cooled with liquid nitrogen was placed between the reactor and the trap.
In that way, unreaeted fluorine was eliminated by
reaction with m e r c u r y and the products not condensed in liquid n i t r o g e n could be analyzed with a Molecular Sieve 5A column of 1/4 in. x 5 ft. with helium as carrier gas in a chromatograph
Vol. 8, No. 5
PHOTOCHEMICAL FLUORINATION
fitted with a gas density detector.
471
Condensable products were
analyzed in every run with a column of dinonylphthalate Chromosorb P (60-80 mesh)
28% on
of 1/4 in. x 8 ft. and nitrogen as
carrier gas. All compounds were identified by I.R. spectra.
Results and D i s c u s s i o n Runs were performed at -4, i0 and 30°C with variation of the initial pressure of F 2 between 40-400 Torr and that of CICN b e t w e e n 5-40 Torr.
In a typical run with 200 Torr of F 2 and 20
Torr of CICN at 30°C and 5% conversion,
it was found that products
were C F 3 C I : N 2 : C F 2 C I 2 : C F 3 N N C F 3 in a ratio 4:2.5:1:0.5 and traces of SiF 4 and COF 2. In the range of pressure was found to depend ~
studied the ratio,
CF3CI/CF2CI2,
some extent on the initial pressure of
F 2 when the ratio of F2/CICN was less than 5, and became independent of F 2 for F2/CICN higher that value
(Table I).
The relation CF3CI/CF2CI 2 diminished with increasing initial CICN pressure and also with increasing temperature,
but the
addition of argon increased the ratio CF3CI/CF2CI 2 (Fig. I). From the information p r e s e n t l y available a realiable m e c h a n i s m seems far from being assessed, approach may be suggested.
however,
a tentative
4"/2
F'HOTO'LHL~'.::C/,.L
FLUORi."<'.
',~<,}o f: ,,~,.,,
1G /
t
/
!4
,/ ./
/
/
i/
//
12
/ /"
/
/
O
~
6
2
//
O0
l'a 10
I'G 1'8
C LCI',I Torr FIG. I
Dependency of RCF3CI/RCF2CI2 with the pressure of cyanogen chloride circles, F 2 only, half filled circles
(with addition
of 400 Torr Argon) and full filled circles addition of 400 Torr Nitrogen), triangles,
IO°C;
squares,
30°C;
-4°C
Initial pressure of fluorine = 200 Tort.
(with
20
~c~l, t . i',o ~q
]~LUORINAT[ON
PHOTOCHEN~ICAL
TABLE
473
i
~<)
3.~
90
~ ~
loo
3.9
200
~.'o
200 +
~.a
4oo
4.1
Initial p r e s s u r e phooolys
of CICN = 20 Torr%
s 25 minutes;
+3 the i n c i d e n t
temn.
time of
30°C
light was 50% less than in
the other runs.
F r o m light m e a s u r e m e n t s of F2
and
from the a b s o r p t i o n
coefficient
(7], the quantum, y i e l d of CF3CI at 30°C w i t h 200 Torr of
F 9 and 200 Torr absorbed
h.¢),
of C I C N was c a l c u l a t e d indicatina
to be 4 (molecules
CF3CI/
a c h a i n mechanism. o
The a b s o r p t i o n fluorine
of light of 3660 A by F 2 p r o d u c e s
atoms of
($) that reacts w i t h CICN giving: F
+
C!CN
~
FCICN
(I)
474
PHOTOCHEMICAL FLUORINATION
These
radicals
turn,
react w i t h F 2 forming
giving
react with F 2 giving
Vol. 8, No. $
CF2CI radicals
CF3CI , or abstract
which,
in
CI from CIC~
CF~CI 2 .
Reaction ent conditions
FCICN
+
F2
~
CF2CI
+
NF
(II)
CF2CI
+
F2
~
CF3CI
+
F
(ili)
CF2C!
+
CICN
CF2CI 2
+
~
IV, may be supported
CN
(IV)
by the fact that under
the ratio C F 2 C I 2 / C F 3 N N C F 3 was always
that C F 3 N N C F 3 is formed by subsequent
reactions
differ-
2, suggesting
of CN w i t h
fluorine. Moreover by experiments photolysis
the a b s t r a c t i o n formed
of CI from CICN can be supported
in this
laboratory
of CF31 in presence
that
showed that in the
of CICN the major product
~s CF3CI
(9). The f o r m a t i o n
of N 2 may be explained
2 NF
a reaction occurs
indeed
N2
reasonable
in shock wave
+
2 F
+
since D i e s e n
experiments.
F2
~
NF 2
of: (v)
(i0) has found
that
(V)
So it could be said that the
reaction NF
on the basis
+
F
Vol. 8, No. 5
PHOTOCHEMICAL FLUORINATION
does not occur.
475
As a matter of fact no traces of N2F4, NF 3 or
some other compound containing N-F bond were found despite exhaustive searching.
Acknowledgment We thank the Consejo Nacional de Investigaciones Cientificas y Tecnicas
(Republica Argentina)
for financial support.
References I.
O. GLEMSER, H. SCHROEDER und H. HAESELER,
Z. anorg, allgem.
Chem., 28~, 80 (1955). 2.
H. L. CRAIG, Diss. Abst., 16, 862 (1956).
3.
H~ J. EMELEUS and G. L. HURST, J. Chem. Soc., 396 (1964).
4o
W. J. CHAMBERS, Soc., 84, 2337 .
C. W. TULLOCK and D. D. COFFMAN, J. Am. Chem. (1962).
J. B. HYNES, B. C. BISHOP and L. BIGELOW,
Inorg. Chem., ~,
417 (1967). .
A. KLEMENC und G. WAGNER,
Z. anorg, allgem.
Chem., 233,
427 (1938). .
R. GATTI, E. H. STARICC0, Z. Physik.
.
J. E. SICRE und H. J. SCHUMACHER,
Chem., 35, 343 (1962).
G. HERZBERG,
Spectra of Diatomic Molecules~ p. 389.
Nostrand Co., Princeton, N.J., 2nd Edition (1950). .
i0.
E. V. OEXLER and E. H. STARICC0, not yet published. R. W. DIESEN, J. Chem. Phys., 45, 759 (1966).
D. Van
NUCL
CHEM
LETTEK~
Vol. ~,~ p~.
THE PHOTOCHEMICAL
46e~-475, 1972,
FLUORINATION
Pergamon
Press,
OF CYANOGEN
Printed
in
Great
13ritair~.
CHLORIDE
E. V. Oexler and E. H. Staricco Departamento Universidad
de Fisicoquimica, Nacional
Facultad
de Cordoba,
de Ciencias
Cordoba
Quimicas
(32), Argentina
(Received 12 danua~ i ~ 2 )
Some attention has been devoted to the fluorination gen chloride
(1-5).
W h e n silver difluoride was used as a fluorin-
ating agent at room temperature yield.
However,
at 100°C
found N2, CF3CI , CF4, products were temperatures N-F bonds
(I), CF3NNCF 3 was produced
(2), besides
CF2C12,
in high
this compound were also
CFCI 3 and CF3NNCF2CI.
A variety of
obtained when. other fluorides were employed at higher (3,4), but in none of these cases were compounds with
isolated.
At 94°C
F 2 among many compounds were
of cyano-
(5), in the reaction between CICN and
a small quantity of CF2CINF 2 and CF3NFCI
obtained. We wish to report that in an attempt
the mechanism
of the fluorination
was undertaken.
to have an insight into
of CICN a study of this system
It was found that no thermal reaction occurs
between CICN and F 2 up to 45°C,
but when the gaseous mixture was
o
irradiated with light of 3660 A, a reaction takes place, CF2CI 2 and N 2 being the major products.
469
CF3CI ,
470
PHOTOCHEMICAL FLUORINATION
Vol. 8, No. 5
Experimental CICN was prepared according to Klemenc to trap distilled at low temperature.
(6), and then trap
F 2 (Air Products) was
twice distilled between liquid oxygen and liquid nitrogen temperatures and stored in a trap cooled with liquid nitrogen. Nitrogen
(99,9%) and Argon
(99,9%) were used without further
purification. The reactor was a quartz cylinder I0 cm long;
it was con-
nected to a quartz spiral manometer used as the reference instrument of a mercury manometer. needle
Aluminum valves with nickel
stems and Teflon gaskets were employed.
The source of
light was a HBO 500 0sram lamp and by means of quartz lens, o
diaphragms and Schott filters a parallel beam of 3360 A was obtained.
The intensity of incident light, measured with a Kipp
compensated thermopile and a Microva Galvanometer,
was 4,54.1015
quantum minute-lcc -I Procedure:
Most of the experiments were carried out to only
few percent conversion.
After the period of illumination the
gaseous mixture was expanded into a trap containing mercury.
A
U-trap cooled with liquid nitrogen was placed between the reactor and the trap.
In that way, unreaeted fluorine was eliminated by
reaction with m e r c u r y and the products not condensed in liquid n i t r o g e n could be analyzed with a Molecular Sieve 5A column of 1/4 in. x 5 ft. with helium as carrier gas in a chromatograph
Vol. 8, No. 5
PHOTOCHEMICAL FLUORINATION
fitted with a gas density detector.
471
Condensable products were
analyzed in every run with a column of dinonylphthalate Chromosorb P (60-80 mesh)
28% on
of 1/4 in. x 8 ft. and nitrogen as
carrier gas. All compounds were identified by I.R. spectra.
Results and D i s c u s s i o n Runs were performed at -4, i0 and 30°C with variation of the initial pressure of F 2 between 40-400 Torr and that of CICN b e t w e e n 5-40 Torr.
In a typical run with 200 Torr of F 2 and 20
Torr of CICN at 30°C and 5% conversion,
it was found that products
were C F 3 C I : N 2 : C F 2 C I 2 : C F 3 N N C F 3 in a ratio 4:2.5:1:0.5 and traces of SiF 4 and COF 2. In the range of pressure was found to depend ~
studied the ratio,
CF3CI/CF2CI2,
some extent on the initial pressure of
F 2 when the ratio of F2/CICN was less than 5, and became independent of F 2 for F2/CICN higher that value
(Table I).
The relation CF3CI/CF2CI 2 diminished with increasing initial CICN pressure and also with increasing temperature,
but the
addition of argon increased the ratio CF3CI/CF2CI 2 (Fig. I). From the information p r e s e n t l y available a realiable m e c h a n i s m seems far from being assessed, approach may be suggested.
however,
a tentative
4"/2
F'HOTO'LHL~'.::C/,.L
FLUORi."<'.
',~<,}o f: ,,~,.,,
1G /
t
/
!4
,/ ./
/
/
i/
//
12
/ /"
/
/
O
~
6
2
//
O0
l'a 10
I'G 1'8
C LCI',I Torr FIG. I
Dependency of RCF3CI/RCF2CI2 with the pressure of cyanogen chloride circles, F 2 only, half filled circles
(with addition
of 400 Torr Argon) and full filled circles addition of 400 Torr Nitrogen), triangles,
IO°C;
squares,
30°C;
-4°C
Initial pressure of fluorine = 200 Tort.
(with
20
~c~l, t . i',o ~q
]~LUORINAT[ON
PHOTOCHEN~ICAL
TABLE
473
i
~<)
3.~
90
~ ~
loo
3.9
200
~.'o
200 +
~.a
4oo
4.1
Initial p r e s s u r e phooolys
of CICN = 20 Torr%
s 25 minutes;
+3 the i n c i d e n t
temn.
time of
30°C
light was 50% less than in
the other runs.
F r o m light m e a s u r e m e n t s of F2
and
from the a b s o r p t i o n
coefficient
(7], the quantum, y i e l d of CF3CI at 30°C w i t h 200 Torr of
F 9 and 200 Torr absorbed
h.¢),
of C I C N was c a l c u l a t e d indicatina
to be 4 (molecules
CF3CI/
a c h a i n mechanism. o
The a b s o r p t i o n fluorine
of light of 3660 A by F 2 p r o d u c e s
atoms of
($) that reacts w i t h CICN giving: F
+
C!CN
~
FCICN
(I)
474
PHOTOCHEMICAL FLUORINATION
These
radicals
turn,
react w i t h F 2 forming
giving
react with F 2 giving
Vol. 8, No. $
CF2CI radicals
CF3CI , or abstract
which,
in
CI from CIC~
CF~CI 2 .
Reaction ent conditions
FCICN
+
F2
~
CF2CI
+
NF
(II)
CF2CI
+
F2
~
CF3CI
+
F
(ili)
CF2C!
+
CICN
CF2CI 2
+
~
IV, may be supported
CN
(IV)
by the fact that under
the ratio C F 2 C I 2 / C F 3 N N C F 3 was always
that C F 3 N N C F 3 is formed by subsequent
reactions
differ-
2, suggesting
of CN w i t h
fluorine. Moreover by experiments photolysis
the a b s t r a c t i o n formed
of CI from CICN can be supported
in this
laboratory
of CF31 in presence
that
showed that in the
of CICN the major product
~s CF3CI
(9). The f o r m a t i o n
of N 2 may be explained
2 NF
a reaction occurs
indeed
N2
reasonable
in shock wave
+
2 F
+
since D i e s e n
experiments.
F2
~
NF 2
of: (v)
(i0) has found
that
(V)
So it could be said that the
reaction NF
on the basis
+
F
Vol. 8, No. 5
PHOTOCHEMICAL FLUORINATION
does not occur.
475
As a matter of fact no traces of N2F4, NF 3 or
some other compound containing N-F bond were found despite exhaustive searching.
Acknowledgment We thank the Consejo Nacional de Investigaciones Cientificas y Tecnicas
(Republica Argentina)
for financial support.
References I.
O. GLEMSER, H. SCHROEDER und H. HAESELER,
Z. anorg, allgem.
Chem., 28~, 80 (1955). 2.
H. L. CRAIG, Diss. Abst., 16, 862 (1956).
3.
H~ J. EMELEUS and G. L. HURST, J. Chem. Soc., 396 (1964).
4o
W. J. CHAMBERS, Soc., 84, 2337 .
C. W. TULLOCK and D. D. COFFMAN, J. Am. Chem. (1962).
J. B. HYNES, B. C. BISHOP and L. BIGELOW,
Inorg. Chem., ~,
417 (1967). .
A. KLEMENC und G. WAGNER,
Z. anorg, allgem.
Chem., 233,
427 (1938). .
R. GATTI, E. H. STARICC0, Z. Physik.
.
J. E. SICRE und H. J. SCHUMACHER,
Chem., 35, 343 (1962).
G. HERZBERG,
Spectra of Diatomic Molecules~ p. 389.
Nostrand Co., Princeton, N.J., 2nd Edition (1950). .
i0.
E. V. OEXLER and E. H. STARICC0, not yet published. R. W. DIESEN, J. Chem. Phys., 45, 759 (1966).
D. Van